Information handling system super elastic spring hinge

ABSTRACT

An information handling system hinge provides friction against rotational motion to generate torque that regulates housing portion relative position. Friction is generated by compression of friction elements with a super elastic wire under tension. For example, a nickel titanium alloy wire under two to eight percent strain provides a relatively low spring rate having consistent compression even as wear reduces the size of the friction elements.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates in general to the field of informationhandling system portable housings, and more particularly to aninformation handling system super elastic spring hinge.

Description of the Related Art

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to users is information handling systems. Aninformation handling system generally processes, compiles, stores,and/or communicates information or data for business, personal, or otherpurposes thereby allowing users to take advantage of the value of theinformation. Because technology and information handling needs andrequirements vary between different users or applications, informationhandling systems may also vary regarding what information is handled,how the information is handled, how much information is processed,stored, or communicated, and how quickly and efficiently the informationmay be processed, stored, or communicated. The variations in informationhandling systems allow for information handling systems to be general orconfigured for a specific user or specific use such as financialtransaction processing, airline reservations, enterprise data storage,or global communications. In addition, information handling systems mayinclude a variety of hardware and software components that may beconfigured to process, store, and communicate information and mayinclude one or more computer systems, data storage systems, andnetworking systems.

Portable information handling systems integrate I/O devices and internalpower to operate free from fixed resources, such as power outlets andperipheral devices. A typical portable information handling systemintegrates a display device to present information as visual images.Often the display device includes a touchscreen that accepts end userinputs. In some cases, touchscreen displays provide the only integratedinput device; however, more advanced systems often include an integratedkeyboard so that an end user can make keyed inputs. Generally,integrated keyboards are built into rotationally coupled housingportions. One housing portion holds the keyboard and acts as a basestand that holds the other portion with the integrated display in aviewing position.

Generally, end users desire low profile and light weight portableinformation handling systems. Minimizing housing size presents achallenge since end users also expect a robust system that will survivemultiple cycles of rotations. Hinges that couple rotating portions toeach other also should provide consistent movement and feel of thehousing portions during rotation. To accomplish these goals, hingestypically generate torque by pressing 2 or more rotating surfacestogether with a force, such as a force generated by compression of aspring. The torques generated is proportional to the coefficient offriction of the contact interface, the force pressing the contactstogether and the mean radius of the contacting area.

In a typical hinge, a stack of Bellville washers are used as a spring togenerate very high loads in a small diameter. The spring rates are veryhigh for this type of spring so that the load generated is sensitive tochanges in compression. To hit a designed nominal torque, the hingemanufacturers calibrate hinges by adjusting a nut that sets compressionon the spring until the desired hinge torque is achieved. However, overtime two main factors contribute to torque changes at a hinge. Onefactor is the change in friction that results as material is removed dueto wear. Material removal decreases the compression distance on thestack of Bellville springs with less compression on a spring meaninggeneration of less torque. Springs with very high spring rates, such asBellville washers tend to have losses in overall torque of the hinge assurfaces wear. Another factor relates to grease or other lubricants usedon friction surfaces to slow down wear. Lubricants reduce wear, however,they also lower the coefficient of friction. As hinges cycle, lubricantstend to slowly migrate out of the friction interface, which increasesthe coefficient of friction and hinge torque over time. Together, thesetwo factors tend to reduce the predictability of hinge performance.

SUMMARY OF THE INVENTION

Therefore, a need has arisen for a system and method which generatestorque at a hinge in a more predictable manner.

In accordance with the present invention, a system and method areprovided which substantially reduce the disadvantages and problemsassociated with previous methods and systems for generating torque at ahinge. A super elastic wire under tension compresses friction elementsthat provide torque responsive to hinge rotation.

More specifically, a portable information handling system integratesprocessing components and a display into rotationally couple housingportions. One or more hinges couple the housing portions to each other,such as to support rotation of the housing portions from closed to openpositions relative to each other. Each hinge has first and secondbrackets that rotate about an axle or similar structure. Frictionelements disposed between portions of the brackets create torque thatopposes rotation of the hinges. To compress the friction elementsagainst each other and create a predictable and repeatable torque, asuper elastic wire is stretched under tension. For example, a nickeltitanium wire under two to eight percent strain compresses the frictionelements so that a constant torque is generated. In one embodiment, thehinge assembles and operates without lubrication. Wear at the frictionelements that changes the size of the friction elements over time doesnot have a substantial impact on compression provided by the superelastic wire due to the super elastic material's low spring rate.

The present invention provides a number of important technicaladvantages. One example of an important technical advantage is that asuper elastic wire compression source maintains a relatively constantcompression force over a wide range of strains to provide a relativelylow spring rate. The low spring rate improves compressive forcepredictability and reduces sensitivity to wear of friction components.Reduced sensitivity to wear reduces or eliminates the need forlubrication at the friction components, resulting in improved torquestability. Ultimately, with higher friction provided by a lack oflubrication, lower compressive force is needed to generate a giventorque so that reduced stress from generation of friction compression isspread across the hinge, allowing for smaller hinge sizes. Furthermanufacture of the hinge is simplified by reducing or eliminating theneed for calibration of torque at the hinge.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood, and its numerousobjects, features and advantages made apparent to those skilled in theart by referencing the accompanying drawings. The use of the samereference number throughout the several figures designates a like orsimilar element.

FIG. 1 depicts a block diagram of an information handling system havinghousing portions rotationally coupled to each other;

FIG. 2 depicts a blown-up view of a hinge having friction compressionprovided by a super elastic wire under tension;

FIG. 3 depicts a spring rate comparison between conventional Bellvillespring and tensioned nickel titanium wire;

FIG. 4 depicts a hinge configured to accept a super elastic wire forcompression of friction elements; and

FIG. 5 depicts an assembled hinge having a tensioned super elastic wirecompressing friction elements.

DETAILED DESCRIPTION

A hinge compresses frictional elements with a super elastic wire undertension to provide torque responsive to hinge rotation, such as forsupporting rotational coupling of information handling system housingportions. For purposes of this disclosure, an information handlingsystem may include any instrumentality or aggregate of instrumentalitiesoperable to compute, classify, process, transmit, receive, retrieve,originate, switch, store, display, manifest, detect, record, reproduce,handle, or utilize any form of information, intelligence, or data forbusiness, scientific, control, or other purposes. For example, aninformation handling system may be a personal computer, a networkstorage device, or any other suitable device and may vary in size,shape, performance, functionality, and price. The information handlingsystem may include random access memory (RAM), one or more processingresources such as a central processing unit (CPU) or hardware orsoftware control logic, ROM, and/or other types of nonvolatile memory.Additional components of the information handling system may include oneor more disk drives, one or more network ports for communicating withexternal devices as well as various input and output (I/O) devices, suchas a keyboard, a mouse, and a video display. The information handlingsystem may also include one or more buses operable to transmitcommunications between the various hardware components.

Referring now to FIG. 1, a block diagram depicts an information handlingsystem 10 having housing portions 12 and 14 rotationally coupled to eachother. Information handling system 10 processes information withprocessing components disposed in base housing portion 12, such as CPU16 that executes instructions to process information, RAM 18 that storesthe instructions and information, and a chipset 20 that manages physicaldevices like graphics and input/output (I/O) devices. Lid housingportion 14 integrates a display that presents information as visualimages, such as with pixel values provided from a graphics processor inchipset 20. A keyboard 22 integrates in the upper surface of basehousing portion 12 to cover the processing components. In operation, anend user rotates lid portion 14 ninety degrees to an open position thatexposes keyboard 22. Hinges 26 attach to each housing portion 12 and 14with a bracket 28 to provide rotational movement of the housing portionsrelative to each other. Hinges 26 include friction elements that providetorque to hold housing portions in position relative to each other. Forexample, a user applies rotational force to move the housing portions toa desired relative orientation and the housing portions remain in therelative orientation until the user applies force again. In alternativeembodiments, alternative types of housing configurations may be used,including detachable keyboard bases or other types of arrangements.

Referring now to FIG. 2, a blown-up view depicts a hinge 26 havingfriction compression provided by a super elastic wire 42 under tension.In the example embodiment, hinge 26 has two brackets that each couple toseparate housing portions. One bracket 28 forms an axle 32 with a tunnel34 through the center. The other bracket 28 extends out a series ofspaced arms that have openings 38 sized to accept axle 32. Frictionelements 36, each also having openings 38 to accept axle 32, fit betweenthe arms of bracket 28 to form a torque generator 30 that creates torqueas brackets 28 rotate relative to each other. The amount of torquecreated by torque generator 30 depends upon the amount of compressionapplied to friction elements 36 once assembled within the arms ofbracket 28. To establish compression, an end cap 40 presses upon one endof torque generator 30 to create a compressive force against bracket 28at the base of axle 32. A super elastic wire 42 inserts through theopenings 38 and tunnel 34 so that a coupling end 44 is exposed at pinrests 46 on opposing sides of torque generator 30. Super elastic wire 42has a length of less than the assembled but uncompressed torquegenerator 30 so that a compressive force is applied by an external toolin order to space for coupling pins 48 to engage coupling ends 44 at pinrests 46. In the example embodiment, friction elements 36 are held in afixed position relative to axle 32 so that, as brackets 28 rotaterelative to each other, friction elements 36 engage against the arms ofthe other bracket 28. In alternative embodiments, alternative ways oftranslating rotational force into friction may be used, as may differentcompressive arrangements for the super elastic wire 42. For example, aloop of wire may couple to one end of a bracket 28 or multiple wires maybe used.

Referring now to FIG. 3, a spring rate comparison is depicted between aconventional Belleville spring and tensioned nickel titanium wire. Inthe example, a nickel titanium alloy wire operating in the super elasticregion has a spring rate nearly forty times lower than the stack of 4Bellville washers. As is evident from the flat portion of the graph, thenickel titanium wire has a fairly constant force over nearly onemillimeter of deflection. In the example graph, 1 mm of deflection onthe wire will stay in the super elastic region for the example wire with2 to 8% strain. Deflection does depend upon wire length with the examplewire having a length of 16-17 mm, however wire length may determine thespring deflection characteristics. For example, a 100 mm long wiredeflects 2 to 8 mm in the super elastic region. Wire diameter thendetermines the amount of force that the wire generates with the wireacting as a pre-loaded extension spring having a very low spring rate.Since the compression remains constant over a greater deflectiondistance, the super elastic wire offers consistent friction generated bythe compressive force even as friction elements wear over time to lessthickness. In order to obtain the consistent compressive force depictedby the flat portion of the graph of FIG. 3, nickel titanium wire isplaced under tension to within a range of two to eight percent ofstrain. In a manufacturing environment, with normal manufacturingtolerances, the nickel titanium wire is designed to have a lengthrelative to the hinge structure that will assemble under tension at asclose to eight percent of strain as possible. For example, strain is setso that the maximum possible strain when accounting for manufacturingtolerance of the assembly is eight percent. With the relatively generousdeflection available at relatively constant compression, assembly withinnormal manufacturing tolerances does not need calibration. As thefriction elements wear over time, the strain can decrease to as low astwo percent with minimal impact on hinge torque. For example, usingtypical friction element wear rates and the spring rate of a nickeltitanium wire, 0.61 mm of material loss would have to occur toexperience a 20% torque degradation. By comparison, with a conventionalBellville spring assembly 0.0016 mm of friction element materialdegradation would produce a 20% torque degradation. Based upon thegreater allowed degradation with the super elastic wire compressiveforce, lubrication between the friction elements may be eliminated sothat coefficient of friction remains constant over time.

Referring now to FIG. 4, a hinge 26 is depicted configured to accept asuper elastic wire 42 for compression of friction elements 36. Ease ofassembly of hinge 26 is illustrated with wire 42 aligned to enter theopenings of the assembled friction elements. Once wire 42 inserts,tension is applied to increase the length of wire 42 so that pins 48insert at each end to hold wire 42 in place and compressing frictionelements 36, in alternative embodiments, alternative devices may be usedto maintain tension on the wire 42.

Referring now to FIG. 5, an assembled hinge is depicted having atensioned super elastic wire compressing friction elements. As indicatedby arrow 50, a tension force applied to wire 42 stretches wire 42 sothat pins 48 insert into coupling ends 44. Torque generator 30 may bemodified to provide desired torque responses based upon rotationalangles. For example, torque generated by friction depends upon thecoefficient of friction of opposing materials and the surface areasubject to frictional forces. Thus, for example, friction elements 36may vary the coefficient of friction or the surface area at differentrelative rotational positions so that torque depends upon rotationalposition. For instance, the last 20 degrees of closing motion of housingportions relative to each other may have less torque to make closing thesystem easier. Similarly, rotational positions that relate to viewingangles may have increased coefficients of friction or surface area sothat housing portions in a viewing position will be less apt to move.

Although the present invention has been described in detail, it shouldbe understood that various changes, substitutions and alterations can bemade hereto without departing from the spirit and scope of the inventionas defined by the appended claims.

What is claimed is:
 1. A method for rotationally coupling informationhandling system housing portions, the method comprising: disposingfriction elements between first and second hinge brackets; compressingthe friction elements against each other with a super elastic wireplaced under tension and coupled to the friction elements; and resistingwith the friction elements rotation of the first and second hingebrackets.
 2. The method of claim 1 wherein the super elastic wirecomprises nickel titanium alloy.
 3. The method of claim 2 wherein thecompressing further comprises: configuring the nickel titanium wire tohave a first length; configuring the friction elements to have a secondlength of greater than the first length; and stretching the nickeltitanium wire to engage the friction elements at the second length. 4.The method of claim 3 wherein the nickel titanium stretches to a wirestrain range of between two percent and eight percent.
 5. The method ofclaim 4 wherein the compressing the friction elements further comprisescompressing friction elements without any lubrication.
 6. The method ofclaim 1 further comprising: forming at least one friction element tohave a contact area that changes based upon a rotational position; andarranging the friction element position to provide reduced torque at apredetermined rotational position based on alignment of the contactarea.
 7. The method of claim 1 further comprising: forming at least onefriction element to have a coefficient of friction that changes basedupon a rotational position; and arranging the friction element positionto provide reduced torque at a predetermined rotational position basedon alignment of the friction element's coefficient of friction.
 8. Themethod of claim 1 further comprising maintaining the superelastic wirein a constant crystal form.